You have a hybrid deployment of Microsoft Exchange Online in Microsoft Office 365 and of your on-premises Microsoft Exchange Server environment. When you try to use the New-MoveRequest Windows PowerShell cmdlet to move or offboard a mailbox from Office 365 to the on-premises environment, the mailbox isn't moved. Additionally, you may receive an error message that resembles the following:
The call to ‘https://webmail.domain.com/EWS/mrsproxy.svc’ timed out. The operation has timed out + CategoryInfo : NotSpecified: (0:Int32) [New-MoveRequest], RemoteTransientException + FullyQualifiedErrorId : 725EBC5,Microsoft.Exchange.Management.RecipientTasks.NewMoveRequest
This issue may occur if incorrect syntax is used for domain names and host names in the New-MoveRequest cmdlet.
To resolve this issue, make sure that you use the correct syntax for domain names and host names in the New-MoveRequest cmdlet. The New-MoveRequest cmdlet requires all domain names and host names to be enclosed in single quotation marks (').
If you experience issues when you move mailboxes to Exchange Online in Office 365, you can run the Troubleshoot Office 365 Mailbox Migration tool. This diagnostic is an automated troubleshooting tool. If you're experiencing a known issue, you receive a message that states what went wrong. The message includes a link to an article that contains the solution. Currently, the tool is supported only in Internet Explorer.